The chart shows the Patrick family’s monthly budget. Make a circle graph to display their budget. Then find how much the family budgets for in each category if their monthly income is $2,500.

Rent and utilities - 35%

Food - 25%

Savings - 10%

Transportation - 15%

Clothing - 10%

Other - 5%

What does the family budget look like? Can you interpret where and how they spend their money?

This Concept is all about interpreting circle graphs. Use it to answer these questions at the end of the Concept.

Guidance

In a
circle graph
, the circle represents the whole.
A circle graph can be used to compare the parts with the whole. It is a useful way to visually display data.
Each of the parts is called a
sector.

Let’s look at how data is expressed in a circle graph.

The circle graph shows how the students at Grandville Middle School voted for a school mascot. Which mascot got the least number of votes?

Since there are no values shown on the circle graph, you need to visually determine which sector is the smallest. The smallest sector is the one for the Panther.

The Panther got the least number of votes for mascot.

The circle graph shows the method of transportation used by students to get to Grandville Middle School. What percent of the students use the school bus to get to school?

The sectors of a circle graph must add up to 100%. Find the sum of the three given percents and then subtract from 100%.

40% of the students use the school bus to get to school.

This circle graph shows the results of a music survey. What fraction of the people surveyed said country was their favorite type of music?

The fractions in the sectors of a circle graph must add up to 1. Find the sum of the three given fractions and then subtract from 1.

of the people surveyed said country was their favorite type of music.

We can show the same circle graph with its percents or with the measures of its central angles. The sum of the measures of the central angles in a circle graph is
.

Notice that you can take the percent, change it to a decimal and multiply it by 360 to find the number of degrees. Check this out with the following examples.

Use the two graphs above to answer the following questions.

Example A

Which number of degrees is equal to 40%?

Solution:

Example B

True or false. 25% is the same as a
angle?

Solution: True

Example C

How many degrees is equal to 15%?

Solution:

Here is the original problem once again.

The chart shows the Patrick family’s monthly budget. Make a circle graph to display their budget. Then find how much the family budgets for in each category if their monthly income is $2,500.

Rent and utilities - 35%

Food - 25%

Savings - 10%

Transportation - 15%

Clothing - 10%

Other - 5%

What does the family budget look like? Can you interpret where and how they spend their money?

Patrick's family spends most of their money on rent, utilities and food. They spend the least amount of money on other things and clothing. These are a couple of statements that we can make about their monthly budget.

Guided Practice

Here is one for you to try on your own.

The table shows the results of the favorite school lunch of students in the seventh grade at Grandville Middle School. Make a circle graph for the results of the survey.

Favorite Food

% of Students Surveyed

Pizza

30%

Grilled Cheese

35%

Hamburger

10%

Chicken fingers

25%

Answer

Step 1: Find the measure of the central angle by multiplying
by the percent.

Favorite Food

% of Students Surveyed

Degrees in Central Angle

Pizza

30%

30% of

Grilled Cheese

35%

30% of

Hamburger

10%

10% of

Chicken fingers

25%

25% of

Step 2: Draw a circle with a compass. Draw one radius. Use that radius as a side of one central angle. Measure and draw the other central anglesusing a protractor.

Step 3: Label each sector with a title and percent and give a title to the entire circle graph.

What about if we have actual data?

If we have actual data, we first need to find the percent for each sector of the circle graph. Then we can find the measures of the central angles of the circle and make the circle graph.